Optical means for producing color cinematographic pictures



April 1, 1930. RT ET AL 1,752,680

OPTICAL MEANS FOR PRODUCING COLOR CINEMATOGBAPHIC PICTURES Filed April19, 1927 Patented Apr. 1 1930 KARL MARTIN AND RAUL TIETZE, OI RATHENOW,GERMANY OPTICAL MEANS FOR PRODUCING COLOR GINEMATOGRAIHIC PICTURESApplication filed April 10, 1897, Serial-No. 185,038, and in GermanyApril 24,1928.

10 this specification and forms part thereof,

illustrates this known-arrangement. a and b I denote here the twoobjectives which are arranged behind a ray-dividing system a. This ingthe dividing system 8, by the reflecting.

portion of the mirror face 0 and is directed toward the objective a bythe fully reflecting face '0, while the pencil of rays required to'produce the component picture 6 passes through the partly light-perviousmirror face i '0 and enters the objective 6. In order to have the twopictures of the same scale for every distance of the objects to betaken, the objectives are displaced relatively to oneanother in axialdirection so that the lengths of the'optical paths on the objectiveside. are the same for both objectives, account being taken of thethickness of the glass. To compensate picture side a glass block 9 hasto be inserted 1n the path 0 the objective a. 0, cl denote the colourfilters interposed before the objectives.

As the distance existing between the middle lines of the componentpictures is very small and amounts, e g., to no more than 12 mm. withthe two-colour process in which the two component pictures are producedin the normal cinematographic size, with the above-described structureof the optical system as shown in Fig. 1 only 6 jectives can be usedthat have a diameter of no more than 12 mm. including their mountings.This rezizystem comprises a mirror face '0 that part-' for thedifierenc'e of the light paths on the sults in a very small'relativeobjective aperture, due to the focal lengths ofobjectives used fortaking moving pictures. 'Such small apertures must be obviatedparticularl in taking polychromatic pictures, for w ich work acomparativel large aperture of the objectives is required To obviatethis drawback, the objectives. are arranged according tov the inventionaway from one another and the picture-producing 0 pencils of raysleaving them are caused to approach one another againby prism systems.Objectives of any desired diameter, that is of anydesired relativeaperture, may be used and the component pictures ma be 65 producednotwithstanding in a common p ane and, as usual, in juxtaposeddisposition.

In order to keep the ray-dividing prism systems as small as possibleconsistent with t e complete covering of the aperture angle of theobjectives, the objectives are arranged at a right, an 1e to one anotherand immediately behin the ray-dividing prisms system in such a mannerthat one objective receives the reflected rays directly and the otherreceives the transmitted ra s directly.

Fig. 2 of the drawing i1 ustrates an embodiment of the improved picturetaking system.

, As in the known arrangement shown in Fig. 1, .9 denotes .theray-dividing system comprising the silver face 41 which is in artpervious to light and in part reflecting. 'n obj ective a" isarranged'to receive the reflected rays directly from the partiallyreflecting surface '0 except for the inter os'ition of a color filter 0.An objective receives the rays transmitted through the reflectingsurface '0 after they pass through a color filter d.

The two objectives a and b are arran ed on axes perpendicular to oneanother an lying at 45 degrees with respect to the plane of thepartially reflecting surface '0 Behind the objectives are two similarand symmetrlcally arranged prisms k and k the exit faces of whichtogether with the plane of the film a,

b are perpendicular to the mirror face '0 The film a, b ismoved past theexit faces of the prisms h, k by drivingsprockets K. The filters a, dare in this case arranged be- 1 I tween the objectives a, b and theprisms h,

k but may be arranged at other positions in the paths of the rays.

, Whatwe claim and desire to ters Patent, is

In a device of the class described, a raydividingdevice comprising apartly lightpervious mirror, a pair of objectives arranged upon axesperpendicular to one another and positioned so that one objectivereceives directly the rays reflected from said mirror,

secure by Let:

,while the other objective receives directly the rays transmittedthrough said mirror, means for passing a film perpendicular at itsmidline to the plane of said mirror, and optical means for turning therays from said objectives into parallel contiguous paths registeringrespectively with the two halves of said film. v y

In testimony whereof the foregoing specification is signed.

' KARL MARTIN.

PAUL TIETZE.

